Python实现多任务进程示例

目录

• 一、进程介绍
• 二、线程和进程之间的对比
• 三、Python 实现多进程
• 四、进程之间的通信
• 五、进程池之间的通信
• 六、案例:文件批量复制

import multiprocessing 
def process(index):
print(f'Process: {index}')
if __name__ == '__main__':
for i in range(5):
p = multiprocessing.Process(target=process, args=(i,))p.start

Process: 0 
Process: 1
Process: 2
Process: 3
Process: 4

from multiprocessing import Process
import timeclass MyProcess(Process):
def __init__(self,loop):
Process.__init__(self)
self.loop = loop
def run(self):
for count in range(self.loop):
time.sleep(1)
print(f'Pid:{self.pid} LoopCount: {count}')
if __name__ == '__main__':
for i in range(2,5):
p = MyProcess(i)
p.start

Pid:12976 LoopCount: 0
Pid:15012 LoopCount: 0
Pid:11976 LoopCount: 0
Pid:12976 LoopCount: 1
Pid:15012 LoopCount: 1
Pid:11976 LoopCount: 1
Pid:15012 LoopCount: 2
Pid:11976 LoopCount: 2
Pid:11976 LoopCount: 3

from multiprocessing import Queue
import multiprocessing
def download(p): # 下载数据
lst = [11,22,33,44]
for item in lst:
p.put(item)print('数据已经下载成功....')
def savedata(p):
lst = 
while True:
data = p.getlst.append(data)if p.empty:
breakprint(lst)def main:p1 = Queuet1 = multiprocessing.Process(target=download,args=(p1,))t2 = multiprocessing.Process(target=savedata,args=(p1,))t1.startt2.startif __name__ == '__main__':
main

数据已经下载成功....
[11, 22, 33, 44]

import multiprocessing
a = 1
def demo1:
global a
a += 1
def demo2:
print(a)def main:
t1 = multiprocessing.Process(target=demo1)t2 = multiprocessing.Process(target=demo2)t1.startt2.startif __name__ == '__main__':
main

from multiprocessing import Pool
import os,time,random
def worker(a):t_start = time.time
print('%s开始执行,进程号为%d'%(a,os.getpid))
time.sleep(random.random*2)
t_stop = time.time
print(a,"执行完成,耗时%0.2f"%(t_stop-t_start))
if __name__ == '__main__':
po = Pool(3) # 定义一个进程池
for i in range(0,10):
po.apply_async(worker,(i,)) # 向进程池中添加worker的任务print("--start--")
po.closepo.joinprint("--end--")

--start--
0开始执行,进程号为6664
1开始执行,进程号为47722开始执行,进程号为132560 执行完成,耗时0.18
3开始执行,进程号为6664
2 执行完成,耗时0.16
4开始执行,进程号为13256
1 执行完成,耗时0.67
5开始执行,进程号为4772
4 执行完成,耗时0.87
6开始执行,进程号为13256
3 执行完成,耗时1.59
7开始执行,进程号为6664
5 执行完成,耗时1.15
8开始执行,进程号为4772
7 执行完成,耗时0.40
9开始执行,进程号为6664
6 执行完成,耗时1.80
8 执行完成,耗时1.49
9 执行完成,耗时1.36
--end--

import multiprocessing
import osimport time

def copy_file(Q,oldfolderName,newfolderName,file_name):
# 文件复制,不需要返回time.sleep(0.5)
# print('\r从%s文件夹复制到%s文件夹的%s文件'%(oldfolderName,newfolderName,file_name),end='')
old_file = open(oldfolderName + '/' + file_name,'rb') # 待复制文件
content = old_file.readold_file.closenew_file = open(newfolderName + '/' + file_name,'wb') # 复制出的新文件
new_file.write(content)
new_file.closeQ.put(file_name) # 向Q队列中添加文件

def main:
oldfolderName = input('请输入要复制的文件夹名字:') # 步骤1获取要复制文件夹的名字(可以手动创建,也可以通过代码创建,这里我们手动创建)
newfolderName = oldfolderName + '复件'
# 步骤二 创建一个新的文件夹if not os.path.exists(newfolderName):
os.mkdir(newfolderName)
filenames = os.listdir(oldfolderName) # 3.获取文件夹里面所有待复制的文件名
# print(filenames)
pool = multiprocessing.Pool(5) # 4.创建进程池
Q = multiprocessing.Manager.Queue # 创建队列,进行通信for file_name in filenames:
pool.apply_async(copy_file,args=(Q,oldfolderName,newfolderName,file_name)) # 5.向进程池添加任务
po.closecopy_file_num = 0
file_count = len(filenames)
# 不知道什么时候完成,所以定义一个死循环while True:
file_name = Q.getcopy_file_num += 1
time.sleep(0.2)
print('\r拷贝进度%.2f %%'%(copy_file_num * 100/file_count),end='') # 做一个拷贝进度条
if copy_file_num >= file_count:
break

if __name__ == '__main__':
main